The present invention relates to an improved plasma etch reactor apparatus and method.
There are a number of prior art devices and methods used for plasma etching of semiconductor wafers. One successful such apparatus and method is disclosed and depicted in U.S. Pat. No. 4,464,223, for which a Reexamination Certificate was issued on Apr. 9, 1991. This plasma etch reactor depicts a reactor chamber which is bounded by three electrodes. An upper electrode is grounded, while a lower electrode is provided with a low frequency power supply along with a DC power supply. The lower electrode is also the chuck which holds the semiconductor wafer in position. Another electrode is located between the upper and lower electrodes and is positioned about the periphery of the reactor chamber in substantially cylindrical in shape. This electrode is provided with a high radio frequency power supply. In this arrangement, the high and low frequency power supplies are used to optimize (1) the disassociation of the process gases, and (2) the ion energy of the plasma generated reactant species.
While the above device has been very successful in operation, it has been found that more precise control of the plasma within the reactor chamber would be beneficial to the operation of a plasma etch reactor.
Accordingly, the present invention is directed to improving upon the operation of prior plasma etch reactors.
It is an object of the present invention to provide a plasma etch reactor which has an increased range of plasma density in order to affect and control the etching processes carried out in the reactor chamber. By way of example only, such enhanced plasma density range can favorably affect the selectivity and the profile control of the etching process.
It is a further object of the invention to provide a solid source which can be eroded to produce gaseous species that are advantageous to the etching process. It is also an object to controllably erode the solid source so that there is an appropriate mixture of the eroded gaseous species and injected process gases.
It is a further object of the invention to provide a unique nozzle arrangement which allows jets of process gas to reach the surface of a semiconductor wafer in order to create a uniform distribution of process gases at the surface.
It is yet a further object of the invention to provide a protruding insulator or baffle in order to further confine the reactor chamber and ensure that there is a uniform distribution of process gases and/or a uniform distribution of process gases mixed with the gaseous species from a solid source.
It is yet another object of the invention to provide an enhanced magnetic field in order to control the plasma created and the amount of gaseous species which are generated from the solid source.
It is a further object of the invention to define the dimensions of the reactor chamber in order to ensure that there is a uniform distribution of fresh process gases at the surface of the semiconductor wafer.
It is yet a further object of the present invention to provide one or more power sources association with one or more of the above features and objects in order to be able to select the desired plasma density within the enhanced range of possible plasma densities by adjusting the power provided to electrodes of the reactor chamber.
Finally, it is still another object of the present invention to provide a reactor chamber which has an increased range of plasma densities due to a combination of any one or all of the above objects and features.
Additional features, objects, and aspects of the invention are evident from the below description and the figures.